1ERF(3) Linux Programmer's Manual ERF(3)
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6 erf, erff, erfl, - error function
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9 #include <math.h>
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11 double erf(double x);
12 float erff(float x);
13 long double erfl(long double x);
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15 Link with -lm.
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17 Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
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19 erf():
20 _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L || _XOPEN_SOURCE
21 || /* Since glibc 2.19: */ _DEFAULT_SOURCE
22 || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
23 erff(), erfl():
24 _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
25 || /* Since glibc 2.19: */ _DEFAULT_SOURCE
26 || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
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29 These functions return the error function of x, defined as
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31 erf(x) = 2/sqrt(pi)* integral from 0 to x of exp(-t*t) dt
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34 On success, these functions return the error function of x, a value in
35 the range [-1, 1].
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37 If x is a NaN, a NaN is returned.
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39 If x is +0 (-0), +0 (-0) is returned.
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41 If x is positive infinity (negative infinity), +1 (-1) is returned.
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43 If x is subnormal, a range error occurs, and the return value is
44 2*x/sqrt(pi).
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47 See math_error(7) for information on how to determine whether an error
48 has occurred when calling these functions.
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50 The following errors can occur:
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52 Range error: result underflow (x is subnormal)
53 An underflow floating-point exception (FE_UNDERFLOW) is raised.
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55 These functions do not set errno.
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58 For an explanation of the terms used in this section, see
59 attributes(7).
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61 ┌──────────────────────┬───────────────┬─────────┐
62 │Interface │ Attribute │ Value │
63 ├──────────────────────┼───────────────┼─────────┤
64 │erf(), erff(), erfl() │ Thread safety │ MT-Safe │
65 └──────────────────────┴───────────────┴─────────┘
67 C99, POSIX.1-2001, POSIX.1-2008.
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69 The variant returning double also conforms to SVr4, 4.3BSD.
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72 cerf(3), erfc(3), exp(3)
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75 This page is part of release 4.15 of the Linux man-pages project. A
76 description of the project, information about reporting bugs, and the
77 latest version of this page, can be found at
78 https://www.kernel.org/doc/man-pages/.
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82GNU 2017-09-15 ERF(3)